import entity.Employee;
import org.junit.Test;

import java.util.*;
import java.util.stream.Collectors;

/**
 * Created by VincentZee on 2019/3/6
 */
public class TestStreamAPI03 {
    List<Employee> emps = Arrays.asList(
            new Employee(102, "李四", 79, 6666.66, Employee.Status.BUSY),
            new Employee(101, "张三", 18, 9999.99, Employee.Status.FREE),
            new Employee(103, "王五", 28, 3333.33, Employee.Status.VOCATION),
            new Employee(104, "赵六", 8, 7777.77, Employee.Status.BUSY),
            new Employee(104, "赵六", 8, 7777.77, Employee.Status.FREE),
            new Employee(104, "赵六", 8, 7777.77, Employee.Status.FREE),
            new Employee(105, "田七", 38, 5555.55, Employee.Status.BUSY)
    );

    //3. 终止操作
	/*
		归约
		reduce(T identity, BinaryOperator) / reduce(BinaryOperator) ——可以将流中元素反复结合起来，得到一个值。
	 */
    @Test
    public void test01() {
        List<Integer> list = Arrays.asList(1, 2, 3, 4, 5, 6, 7, 8, 9, 10);
        Integer sum = list.stream().reduce(0, (x, y) -> x + y);
        System.out.println(sum);

        Optional<Double> optionalDouble = emps.stream().map(Employee::getSalary).reduce(Double::sum);
        System.out.println(optionalDouble.get());
    }

    // 需求：搜索名字中 “六” 出现的次数
    @Test
    public void test02() {
        Optional<Integer> sum = emps.stream().map(Employee::getName)
                .flatMap(TestStreamAPI01::filterCharacter)
                .map((ch) -> {
                    if (ch.equals('六'))
                        return 1;
                    else
                        return 0;
                }).reduce(Integer::sum);

        System.out.println(sum.get());
    }

    // collect——将流转换为其他形式。接收一个 Collector接口的实现，用于给Stream中元素做汇总的方法
    @Test
    public void test03() {
        List<String> list = emps.stream().map(Employee::getName).collect(Collectors.toList());
        list.forEach(System.out::println);
        System.out.println("-------------------");
        Set<String> set = emps.stream().map(Employee::getName).collect(Collectors.toSet());
        set.forEach(System.out::println);
        System.out.println("-------------------");
        HashSet<String> hashSet = emps.stream().map(Employee::getName).collect(Collectors.toCollection(HashSet::new));
        hashSet.forEach(System.out::println);
    }

    @Test
    public void test04() {
        Optional<Double> max = emps.stream()
                .map(Employee::getSalary)
                .collect(Collectors.maxBy(Double::compare));

        System.out.println(max.get());

        Optional<Employee> op = emps.stream()
                .collect(Collectors.minBy((e1, e2) -> Double.compare(e1.getSalary(), e2.getSalary())));

        System.out.println(op.get());

        Double sum = emps.stream()
                .collect(Collectors.summingDouble(Employee::getSalary));

        System.out.println(sum);

        Double avg = emps.stream()
                .collect(Collectors.averagingDouble(Employee::getSalary));

        System.out.println(avg);

        Long count = emps.stream()
                .collect(Collectors.counting());

        System.out.println(count);

        System.out.println("--------------------------------------------");

        DoubleSummaryStatistics dss = emps.stream()
                .collect(Collectors.summarizingDouble(Employee::getSalary));

        System.out.println(dss.getMax());
    }

    // 分组
    @Test
    public void test05() {
        Map<Employee.Status, List<Employee>> map = emps.stream().collect(Collectors.groupingBy(Employee::getStatus));
        System.out.println(map);
    }

    //多级分组
    @Test
    public void test06() {
        Map<Employee.Status, Map<String, List<Employee>>> map = emps.stream()
                .collect(Collectors.groupingBy(Employee::getStatus, Collectors.groupingBy((e) -> {
                    if (e.getAge() >= 60)
                        return "老年";
                    else if (e.getAge() >= 35)
                        return "中年";
                    else
                        return "成年";
                })));

        System.out.println(map);
    }

    // 分区
    @Test
    public void test07() {
        Map<Boolean, List<Employee>> map = emps.stream()
                .collect(Collectors.partitioningBy((e) -> e.getSalary() >= 5000));

        System.out.println(map);
    }

    //
    @Test
    public void test8() {
        String str = emps.stream()
                .map(Employee::getName)
                .collect(Collectors.joining(",", "----", "----"));

        System.out.println(str);
    }

    @Test
    public void test9() {
        Optional<Double> sum = emps.stream()
                .map(Employee::getSalary)
                .collect(Collectors.reducing(Double::sum));

        System.out.println(sum.get());
    }
}
